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<head>
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    <style>
        body {
            padding: 100px;
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        div {
            width: 300px;
            height: 300px;
            border: solid 2px #ddd;
            /* box-shadow: 0 0 5px rgba(100, 100, 100, .2); */
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        .s-shadow {
            box-shadow: 0 0 5px rgba(100, 100, 100, .2);
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        .m-shadow {
            box-shadow: 0 0 8px rgba(100, 100, 100, .8);
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        <div class="m-shadow">houdunren.com</div>
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